This forward is not part of this Telecommunications Systems Bulletin (TSB)

This TSB is the product of work undertaken by the Electromagnetic Energy (EME)working group of the TIA TR8.17 RF Exposure subcommittee. The subcommitteeaddresses Radio Frequency Exposure matters. TR8.17 is a subcommittee of TIA TR8Mobile and Personal Private Radio Standards Engineering Committee. This TSB wasrevised and approved for publication at the October 16, 2008 meeting of TR8.17. Themotion to publish was ratified at the January 22, 2009 meeting of TR8.17.

Thereare

two

annexes,AnnexA

and Annex B, in this TSB andboth are

informative.

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v

Patent Identification

The reader’s attention is called to the possibility that using this document mightnecessitate the use of one or more inventions covered by patent rights. By publicationof this document no position is taken with respect to the validity of those claims or anypatent rights in connection therewith. The patent holders so far identified have, webelieve, filed statements of willingness to grant licenses under those rights onreasonable and nondiscriminatory terms and conditions to applicants desiring to obtainsuch licenses. The following patent holders and patents have been identified inaccordance with the TIA intellectual property rights policy:

−

None identified

TIA is not be responsible for identifying patents for which licenses might be referencedby this document or for conducting inquiries into the legal validity or scope of thosepatents that are brought to its attention.

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1.

Introduction

1.1.

Scope

This TSB establishes and documents methods and procedures of evaluation toestablish compliance of fixed station cabinet emission levels with respect to the FederalCommunications Commission (FCC) electromagnetic exposure (EME) limits.Specifically the EME

characterization is of box level equipment only, e.g., a fixedstation, control station, or similar equipment, This TSB is not a substitute for a completetransmitter site environmental assessment (EA) by means of computational methods orsite measurement

or a combination of these two means. A limit case analysis based onthe 47 CFR part 90 certification requirements for spurious emissions limits includedherein shows that certified equipment at the box level is within the FCC maximumpermissible exposure

(MPE) limits.

2.

References

This Telecommunications System Bulletin contains only informative information.

There are references to TIA standards which contain normative elements. Thesereferences are primarily to indicate the methods of measurement contained

in thosedocuments. At the time of publication, the edition indications were valid. All standardsand bulletins are subject to revision, and parties to agreements based on this documentare encouraged to investigate the possibility of applying the most recent edition of thestandard or bulletin indicated in Section 3. ANSI and TIA maintain registers of currentlyvalid national standards published by them.

There are references to FCC rules. The Federal Code of Regulations (CFR) is subjectto revision. The Government Printing Office (GPO) maintains a listing of the latestpublished titles.

3.

FCC Electromagnetic Emission Limits

Controlled and general populationRF Exposure Limitsare

shown in Table

1, below.

TheRF Exposure Limits shown in Table 1 are the limits adopted by the FCC. The RFexposure limits adopted by the FCC are generally based on recommendations from theNational Council on Radiation Protection and Measurements (NCRP) Report No. 86and the American National Standards Institute (ANSI/IEEE) C95.1-1992.1

This analysis is structured to show that equipment that conforms to FCC emission limitsfor the carrier and its harmonics, through the tenth, will result in an equipment levelEME that is compliant to the MPE limits as set forth in 47 CFR § 1.1310.

4.1.

Calculation of EME level based on the FCC limit of-13 dBm for

each of

the

transmitter harmonics (1-10).

The limit case calculation will compute the resultant EME level, as a percent of the MPElevel, of a transmitter that exhibits the maximum allowable cabinet emission limits asdefined in 47 CFR § 90.210. This maximum level is a spurious emission that isattenuated by at least 43 + 10 log(P) dB, with P being the transmitter average power inwatts or equivalently-13 dBm.

The cabinet emissions are considered to be emitted from a point source. As such it isnecessary to define a distance at which the power density will

RF and Microwave”recommendation of a minimum separationdistance of 20 cmbetween the probe and theperturbing object.

This will allow controlled population to be sufficiently close to theequipment to allow direct observation or normal service interface through a terminaldevice or similar equipment.

4.2.

Example spreadsheet calculations

Calculation method:

1.

Compute the power density, S, using equation 1, for each harmonic at the maximumallowable FCC radiated level (-13 dBm), at the specified distance, 20 cm, for thehorizontal polarization, “where Prad is the power radiated”.

S = (Prad

x 1.64)/(

x r

2) mW/cm2, r=20 cm

(1)

Prad

is the radiated power

(mW)

R

is the minimum working distance

(cm)

2.

Compute percent of MPE for each harmonic using equation 2.

%MPE(fn) = 100 x S(fn)/MPE(fn)

(2)

MPE(fn)

is the allowable MPE for each transmitter harmonic

, n = 1 to 10;

S(fn)

is the power density for each transmitter harmonic, n = 1 to 10;

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4

3.

%MPE(h) = Sum of %MPE(fn), n = 1-10.

%MPE(h)

is the percent of the maximum permissible exposure in the horizontalpolarization

4.

Repeat steps 1-3 for vertical polarization.

5.

Total %MPE = %MPE(h) + %MPE(v)

4.3.

Calculations at representative frequencies 3 MHz–

2GHz

Tables

showing the complete set of calculations (horizontal and vertical polarization) foreach frequency and its harmonics are included in Annex A. Table 2 belowshows thehighest level computed for each of the various Fundamental Frequencies shown inAnnex A.

Table1

MaximumResultant Controlled and General Population Percentage of

FCCMPElimits

for each Fundamental Frequency shown in Annex A

FundamentalFrequency(MHz)

Controlled

Population

% MPE

General

Population

%MPE

3

1.26E-02

6.30E-02

30

3.27E-02

1.64E-01

450

8.58E-03

4.29E-02

900

6.98E-03

3.49E-02

1900

6.54E-03

3.27E-02

The highest(worst case)computed level, as shown in Table2,

above at a FundamentalFrequency of 30 MHz, is more than 600 times [1/(1.64E-01/100)=609.8] below the FCCMPE limits.However, one must consider what would happen if there were someadditional spurious energy that was not at the harmonic frequencies. To reach the MPElimits at the Fundamental Frequencyof 30 MHzwould require a total of approximately6000 individual spurs, with eachspurradiating at exactly the FCC spurious limit withequal horizontal and vertical polarized energy. In practice the spurious emissions froma cabinet will include transmitter harmonic content and spurious emissions from clocksand references that are associated with control and signal processing functions. While,industry experience has shown that the transmitter harmonic responses are the primaryTSB-92-A

5

contributors to the spurious emissions, each transmitter design should be carefullyassessed with respect to non-harmonic content.

4.4.

Measurement method

The measurement method is as stated in TIA-603-C clause 2.2.12 Radiated SpuriousEmissions with the following modification:

The carrier-radiated emission, terminated in a non-radiating load, must also bemeasured for horizontal and vertical polarization.

5.

Transmitter Site Considerations

5.1.

Site compliance

The

analysisin this TSBindicates compliance with theFCCequipment certificationrequirements for equipmentsused at

a transmitter site,in and of themselves should notexceed the RF exposure limits established by the FCC.

To assure that any transmitter site whether a base station site,

a control station site or asimilar transmitting facility complies with the FCC exposure limits, all site operators areremindedan RF Safety Program that includes procedures for"Evaluating Compliancewith FCC-Specified Guidelines for Human Exposure to Radiofrequency Radiation"

is within recommended MPE level limits, but does not imply that theoveralltransmittersite conforms to FCC MPE guidelines. Additional computations or measurements or acombination of both at each transmitter site will determine what precautionsandoperational proceduresare necessary for each particular site to meet MPE guidelines.Proper installation of antenna distribution systems, work practices, etc. are required fora site to conform with FCC guidelines for human exposure to electromagnetic energy.

Manufacturers ofFCCcertified transmitter site

equipment are strongly encouraged toadvise allusers, in their product documentation and elsewhere,

that utilization of FCCcertified transmitter site equipmentdoes not in and of itself constitute completecompliance with all FCC RF safety requirements.

and maintained, does not constitute an EME hazard. This does not imply thata particular site

where suchFCC certified equipment

is utilized, is in fact a non-hazardous transmitter installation. The FCC limits for cabinet RF emissions assuresthat unintentional cabinet emissions, at distances suitable for maintenance activities,are below the FCC MPE limits. However, the levels of intentional emission must becharacterized by means of computation or measurement, to determine what precautionsand work practices must be adhered to for each transmitter site.